So-called storage systems have been known that include subsystems configured with disk arrays composed of a plurality of magnetic disk drives or flash memory drives and store data in the disk arrays.
As disclosed in United States Patent Application Publication No. 2007/0201434 A1 (PTL 1), for example, a storage system is configured to include host interfaces for connecting to host computers, hard disk drives (HDDs) or solid state drives (SSDs), disk interfaces for communicating with the drives, cache memory modules for temporarily storing data to improve the performance of the storage system, and processors that receives access requests from the host computers and controls data transfers.
A large-scale storage system includes, for example, about 2,000 of disk drives, external interface with 200 ports for host computers on aggregate, and about 1-TB cache memory capacity.
Such a large-scale storage system may use buffer memories in data transfers from disk drives to host computers, like the system disclosed in “IBM System Storage DS8700 Architecture and Implementation, IBM Corporation, August 2010” (NPL 1).
For example, a large-scale storage system stores data in buffers of the disk interface or the host interface in addition to cache memories in the process from retrieving data from a disk drive until delivering it to a host computer. This configuration allows circuits such as the disk interface and the host interface to operate independently, so that the throughput of the overall system can be improved.